Spatial perturbation caused by a badger (Meles meles) culling operation: implications for the function of territoriality and the control of bovine tuberculosis (Mycobacterium bovis).

1. The spatial organization of a badger population (North Nibley) is described before and after it was subjected to a UK Ministry of Agriculture, Fisheries and Food badger removal operation (BRO) intended to control bovine tuberculosis. Comparison is made with an undisturbed badger population (Woodchester Park). 2. The Woodchester Park population was organized in group territories with clearly defined boundaries that remained stable during the 3 years of study (1995-97). In North Nibley, however, the badgers' spatial organization was severely perturbed in the first year and, to a lesser extent, also in the second year after the BRO, with badgers using latrines further away from their setts. This resulted in enlarged social group ranges that were difficult to define and overlapped considerably. 3. The disturbance was observed in the removal groups, those immediately adjacent, as well as those at a distance of one or two social groups from the removal area, with an unexpected indication that the latter groups may have been the most affected. 4. The apparent increase in the size of the group ranges in North Nibley was likely to have been caused by an increased proportion of badgers making extra-group excursions in the aftermath of the BRO. 5. Initial recolonization was almost exclusively by females. 6. Although such perturbation might be expected to facilitate disease transmission between badger social groups, there was no evidence that any infectious animals had survived the BRO. However, there were further cattle breakdowns in the area. 7. The behaviour of badgers after the BRO also provided an opportunity to test predictions made by competing hypotheses about the main determinants of the badger's socio-spatial behaviour.